Sheet separating device for photocopying machine

ABSTRACT

A SHEET SEPARATING DEVICE FOR AN ELECTROSTATIC CONTACT TYPE COPYING MACHINE. THE SEPARATING DEVICE IS FORMED OF A THIN WEB OF TRANSPARENT MATERIAL WHICH HAS ON THE EXIT SIDE A SHEET DIVERTER FORMED OF A PAIR OF DIVERGING SECTIONS EACH OF WHICH SECTIONS FLARE OUTWARDLY.

Sept. 20, 1971 E. J. PETRICK EIAL 3,606,309

SHEET SEPARATING DEVICE FOR PHOTOCOPYING MACHINE Filed May 1, 1970sum/4R0 1 PETE/CK AAYMOA/D SCf/M/OL //v ATTUENEY United States Patent O3,606,309 SHEET SEPARATIN G DEVICE FOR PHOTOCOPYING MACHINE Edward J.Petrick, Euclid, and Raymond J. Schmidlin,

Lyndhurst, Ohio, assignors to Addressograph-Multigraph Corporation,Cleveland, Ohio Filed May 1, 1970, Ser. No. 33,674 Int. Cl. B65h 29/64US. Cl. 271-64 9 Claims ABSTRACT OF THE DISCLOSURE A sheet separatingdevice for an electrostatic contact type copying machine. The separatingdevice is formed of a thin web of transparent material which has on theexit side a sheet diverter formed of a pair of diverging sections eachof which sections flare outwardly.

I BACKGROUND OF THE INVENTION This invention relates generally toseparating devices, and more particularly to devices for separating anoriginal and a copy sheet after exposure of the original onto the copysheet in a photocopying machine. The invention is particularlyapplicable to and useful in photocopying machines which utilize thecontact exposure process of reproducing images from the original sheetonto a copy sheet. In such a device, the original and copy sheets areintroduced into the machine and are transported past an exposure zone orstation in face-to-face contact at which zone the copy sheet is exposedto produce a latent image of the material on the original. After leavingthe exposure zone, the original and the copy sheets must be separated sothat the copy sheet can be further processed to develop the latent imagethereon, and the original ejected from the machine.

There have been several prior art proposals for separating the originaland copy sheets. For example, it has been proposed that air be blown onthe edges of the two sheets to cause a separation thereof. This has notproved entirely satisfactory, since the blowing of air does not assure aseparation. Also, it has been proposed to utilize a plurality oflongitudinally extending thin transparent filaments, which filamentsextend from the entrance side to the exit side of the exposure zone andare interposed between the two sheets. The filaments are arranged sothat alternate filaments are on divergent planes on the exit side so asto effect a separation of the sheets. This scheme also has severaldrawbacks. First, the use of a multiplicity of elements provides aconfiguration wherein the edges of either the original document or thecopy sheet can become caught on the wrong side thereof, thus not onlyfailing to provide document separation, but also actually damaging thedocuments. This is especially true when documents of different widthsare to be copied by the machine since for certain widths one of thefilaments will be located close to the edge of the documents making iteasy for the edge to slip on the wrong side thereof.

Another of the drawbacks to these filaments is that, in order to obtainsuflicient strength, the filaments have -had to have substantialthickness. This thickness is usually great enough to cause documentseparation of suflicient magnitude that undercutting of the lightoccurs, resulting in streaking or lining of the copy at the location ofthe filaments when the copy sheet is exposed. Even controlling the shapeand configuration of these filaments has not completely eliminated theproblem of lining or streaking of the copy sheet.

SUMMARY OF THE INVENTION According to the present invention, a sheetseparator for separating a copy sheet from an original sheet in aphotocopying machine is provided which includes a longitudinallyextending web of transparent material. The web of material has a centralportion at the exposure station and opposite end positions at theentrance and exit sides of the exposure station. The transparentmaterial, especially at the central portion, is relatively thin,preferably less than .001" thick, and has a width sufficient to preventbreakage when it is maintained under tension. The portion of the web onthe exit side has a sheet diverter and formed of a pair of sectionswhich extend from the central portion on diverging planes, and eachdiverging section also flares laterally and longitudinal- 1y, i.e.,increase in width along the length thereof, to provide effectiveseparation.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view somewhatdiagrammatic showing the sheet separating device of this invention asused in the mechanism of an electrostatic copying machine;

FIG. 2 is a sectional view taken substantially along the planedesignated by the line 2-2 of FIG. 1; and

FIG. 3 is a plan view of the sheet separating device of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawing,and for the present to FIGS. 1 and 2, there is illustrated, somewhatdiagrammatically, the exposure section of a contact type of photocopyingmachine together with the entrance and exit sections on opposite sidesthereof.

The illustrated portion of the photocopying machine includes an exposurestation designated generally as 10, which has a light source 12surrounded by a reflector 14. The reflector 14 has a transverselyextending opening 16 defined by a retainer plate 18 secured to thereflector and disposed to provide a uniform opening for the emission oflight from the light source 12.

The retainer plate 18 constitutes the support member for one of thesheets which travel past the exposure station 10. Disposed on theopposite side of the retainer plate 18 is a longitudinally extendinggenerally U-shaped support bar 20 which has secured thereto by means ofscrews 21 a sheet of relatively resilient material 22 having a lowcoefficient of sliding friction such as Mylar or a similar type plastic.The plastic material 22 serves as a pressure member bearing against theretainer plate 18 and will urge the sheets to be copied into engagementwith each other and against the retainer plate as they pass the exposurestation.

On the entrance side of the exposure station ,10 are disposed a pair ofentry rolls 23 and 24 which are journalled for rotation in the directionindicated by the arrows and on the exit side of the exposure station 10are a pair of exit rolls 25 and 26 journalled for rotation in thedirection shown by the arrows. The rolls 23', 24, 25 and 26 are adaptedto engage and transport a pair of superimposed flat sheets designated bythe arrowed lines 28 and 30 (FIG. 2) to and through the exposure station10. The sheet 28 represents an electrostatic copy sheet having 2.treated surface which is disposed to be in contact with the face ofsheet 30, which represents an original document to be copied. The entryrolls 23 and 24 engage the sheets 28 and 30 and drive them to and pastexposure station 10. When the sheets 28 and 30 emerge from the exposurestation 10, they are engaged by the rolls 25 and 26 so that the rolls23, 24,

25 and 26 act in conjunction with each other to provide a positive feedmechanism for the original and copy sheets.

When the sheets 28 and 30 have been exposed, it is necessary that thecopy sheet 28 be further processed to develop the latent image, and theoriginal sheet 30 must be returned. Thus, the sheets require separation.In order to effect the separation of these sheets, a sheet separatingstructure is provided. The sheet separating structure includes a web ofclear transparent plastic film designated generally as 32. This web,which can best be seen in plan view in FIG. 3, includes a longitudinallyextending central portion 34 which terminates on one end thereof with anentrance bar engaging portion 36 having a plurality of apertures 38disposed to engage with screws 40 on entrance bar 42.

The opposite end portion of the plastic film 32 on the exit side isformed with a sheet diverter 43. The sheet diverter 43 includes a returnend piece of the plastic film- 32 which is heat-sealed as shown at 44 toform a loop 46. The loop 46 is disposed to engage an exit bar 48 so thatthe diverter 43 has a pair of diverging sections 50 and 52 extending ondiverging planes.

As can best be seen in FIG. 3, the sections 50 and 52 each flare rapidlyoutwardly from the narrow central portion 34 to a relatively wide end 54which preferably extends substantially the entire width of the widestcopy sheet to be used in the machine.

The plastic film 32 is disposed in the copy machine with the centralportion 34 thereof extending centrally of the rollers 23, 24, 25 and 26,and centrally of the exposure station 10. The rollers each have centralrelief portions (unnumbered) so that they will not drivingly engage theplastic web. The plastic film 32 is formed of a transparent materialwhich can be maintained taut to prevent any wrinkling thereof and thesurfaces of which have a relatively low coefficient of sliding frictionto allow the original and copy sheets to slide therealong withoutcatching or without damaging the sheets. It is preferred that thethickness of the central portion 34, especially where it is adjacent theopening 16, be less than .001" thick. If the thickness of the webmaterial is greater than .001", the separation of the sheets beingcopied is sufiiciently great so that there is a distortion of the image.Further, with separation of more than .001" there is a tendency towardthe phenomenon of undercutting of the light along the edges of the web,which phenomenon results in the appearance of lines on the finished copyat the locations of these edges. However, with a thickness of less than.001", good image reproduction is obtained and the phenomenon ofundercutting by the light is not present.

One suitable material for the plastic web is clear Mylar plasticapproximately .00075" thick. With Mylar plastic of this thickness, avery satisfactory width of the central portion 34 is A". This widthprovides suflicient strength to maintain the plastic under tensionwithout the plastic breaking or tearing. It is understood, however, thatany width of the central portion can be utilized provided it issufliciently wide to provide the necessary strength to resist breakingor tearing.

With respect to the maximum width of the plastic film, this is dictatedmerely by the nature of the equipment being utilized. In the disclosedembodiment, rollers are utilized to feed two sheets past the exposurestation 10. Hence the rollers 23, 24, 25 and 26 must contact the sheetsin order to drivingly engage them, and thus the width of the plastic, atleast in the vicinity of the rollers must be narrower than the sheets ofmaterial which are to be utilized in the machine in order that therollers can grip and drive them. Otherwise there is no maximum width.

In the operation of the sheet separating device, the sheets 28 and 30are fed into the rolls 23 and 24 from opposite sides of the entrance bar42, as shown in FIG. 2. The rolls 23 and 24 drive the sheets to theexposure station 10, and the pressure member 22 presses the sheets 28and 30 firmly together and firmly against the retainer plate 18 as theypass the exposure station. The light from the light source 12 passesthrough the opening 16 and exposes the copy sheet 28 to the image on theoriginal sheet 30. From the exposure station 10 the rollers 25 and 26engage the superimposed sheets 28 and 30 and continue to drive themtoward the sheet diverter 43.

While the sheets 28 and 30 have been passing between the rollers 23, 24,25 and 26, and past the exposure station 10, the central portion 34 ofthe plastic web 32 has been interposed between the sheets centrallythereof while the remainder of the sheets 28 and 30 have been infaceto-face contact. As the sheets reach the sheet diverter 43, thediverging sections 50, 52 of the loop configuration acts as a diverterfor the sheets 28 and 30 as shown in FIG. 2. This diverting action ofthe sections 50 and 52 will gradually divert the sheet 28 on anangularly upward path, and the sheet 30 on an angular downward path.Also, the outwardly flaring configuration of the sections 50 and 52progressively engages a greater and greater width of the sheets 28 and30 so that at the end of the exit bar 48 essentially the entire width ofboth of the sheets are engaged by the plastic web 30, thus havingeffected complete separation of the sheets.

Therefore, it can be seen that, in essence, the separation of the sheetsas they emerge from the exit rolls 25 and 26 is the result of a dualtype of action by the sections 50 and 52 on the sheets 28 and 30. As thesheets progress, they are progressively engaged by a wider and widersegment of the plastic sheet 32 causing separation, and also thediverging sections 50 and 52 guide the sheets to divergent paths,resulting in what could be characterized as a peeling action,essentially peeling the two sheets from each other.

In order to achieve this type of peeling action, the sections 50 and 52of the sheet diverting section 43 flare outwardly as shown in FIG. 3with these outwardly flaring portions each subtending an angle withrespect to a line normal to the longitudinal axis of the machinedesignated as a in FIG. 3. It is desirable that angle a be as large aspossible. However, in most machines, there are serious space limitationsso that from a practical point of view, it is difficult to obtain anoptimum large angle. However, in order to provide an effective peelingaction, as above described, it is necessary that this angle a be atleast 7 degrees, and preferably it should be greater than 10 degrees. Anangle of 11 degrees has proved to be satisfactory. If this angle is lessthan about 7 degrees, there is a rather marked tendency for the edges ofthe sheets 28 and 30 to engage the edges of the sections 50 and 52,causing damage and, in fact, in some cases jamming the sheets in themachine. This tendency toward engagement of the edges is reducedmarkedly above 7 degrees and is virtually eliminated above an angle of10 degrees.

What is claimed is: 1. In an apparatus having a station at which twosheets are in superimposed relationship with each other; the combinationof; drive means, and sheet separating means, said drive means beingdisposed to drive said sheets past said station from an entrance sidethereof to an exit side thereof;

said sheet separating means including a web of transparent materialhaving a central portion, means mounting said web of material with oneend portion thereof at the entrance side of the station and the oppositeend portion at the exit side of the station with the central portiondisposed at the station, said Web of material having a sheet diverter atthe end portion thereof on the exit side of the station, said sheetdiverter including a pair of sections lying on planes diverging from theplane of said central portion and disposed to guide the two sheets ondiverging paths to separate the sheets after they emerge from thestation.

2. The invention as defined in claim 1 further characterized by saiddrive means including drive rolls for drivingly engaging said sheets;

said sheet separating means extending beyond said drive rolls, and saiddrive rolls included recessed portions to accommodate said centralportion of the sheet separating means without driving engagementtherewith.

3. The invention as defined in claim 1 wherein at least the centralportion of the web is no greater than approximately .001" thick.

4. The invention as defined in claim 1 wherein said diverging sectionseach flare outwardly from the central portion from a narrow to a widewidth.

-5. The invention as defined in claim 4.wherein the edges of saidoutwardly flaring sections subtend an angle of at least 7 deg. withrespect to a line normal to the center line of the web.

6. The invention as defined in claim 4 wherein said outwardly flaringsections subtend an angle of at least 10 deg. with respect to a linenormal to the center line of the web.

7. The invention as defined in claim 1 wherein said pair of divergingsections constitute opposite portions of a loop formed at the' endportion of the web of material.

8. The invention as defined in claim 7 wherein said loop engages an exitbar, which bar maintains the web under tension.

9. The invention as defined in claim 1 wherein said central portion ofthe web of material is substantially narrower than the narrowest sheetto be copied.

References Cited v UNITED STATES PATENTS 113,769 4/1871 Hoe Z7164X853,480 5/ 1907 Smith 2715l 3,386,730 6/1968 Hyosaka 271--64 JOSEPHWEGBREIT, Primary Examiner B. H. STONER, Ira, Assistant Examiner U.S.c1. X.R. 271-51, Dig. 2

